Switching device for a brake system for a vehicle, brake system with a switching device and method for operating a switching device

ABSTRACT

A switching device for a vehicle brake system, including: a central-control-unit (CCU) for controlling the brake system, at least one subsystem-control-unit (SCU) which is connected/connectable to the CCU via a data bus to control a subsystem device of the brake system and/or a redundant-control-unit (RDC) which is connected/connectable to the CCU via a further data bus to control a redundant brake system for the brake system; and a monitoring device to read in a first test signal from the CCU to test a function of the CCU and which is configured to read in a second test signal from the SCU to test a function of the SCU and/or to read in a redundant test signal from the RDC to test a function of the RDC. Also described are a related brake system, a method, and a computer readable medium.

FIELD OF THE INVENTION

The present approach relates to a switching device for a vehicle brakesystem, a brake system having a switching device, and a method foroperating a switching device.

BACKGROUND INFORMATION

As part of the automated or autonomous driving of all types of vehicles,it is necessary to create redundancies. These redundancies must beconfigured in such a way that the vehicle cannot be placed in asafety-critical or uncontrollable condition. For example, redundanciescan be achieved by configuring systems in duplicate or by linking themto other systems that perform similar functions. In accordance with thespecifications of Functional Safety Standard ISO26262-2,microcontrollers of control units must be monitored by an externalentity.

SUMMARY OF THE INVENTION

Against this background, the object of this approach is to provide animproved switching device for a vehicle brake system, an improved brakesystem with a switching device, and an improved method for operating aswitching device.

This object may be achieved by a switching device having the featuresdescribed herein, by a brake system described herein, by a methoddescribed herein, and by a computer program described herein.

The advantages achievable with the proposed approach are savings on thecosts of additional controllers or integrated circuits with watchdogsfor monitoring each individual control unit of a brake system.

A switching device for a brake system for a vehicle comprises a centralcontrol unit, at least one subsystem control unit and, in addition oralternatively, a redundant control unit and a monitoring device. Thecentral control unit is configured to control the brake system. Thesubsystem control unit is connected or can be connected to the centralcontrol unit via a data bus and is configured to control a subsystemdevice of the brake system. The redundant control unit is connected orcan be connected to the central control unit via an additional data busand is configured to control a redundant brake system for the brakesystem. The monitoring device is configured to read in a first testsignal from the central control unit in order to test a function of thecentral control unit, and to read in a second test signal from thesubsystem control unit in order to test a function of the subsystemcontrol unit, and additionally or alternatively to read in a redundanttest signal from the redundant control unit in order to test a functionof the redundant control unit.

The brake system can be an electronic brake system, or “EBS” for short.The central control unit, the subsystem control unit and additionally oralternatively the redundant control unit, can each have at least onemicrocontroller. The redundant control unit can be configuredfunctionally identical to the central control unit, for example alsoidentical in configuration. The subsystem can be any type of brakemodule of the brake system, for example an electropneumatic module or afoot brake module. The redundant brake system can be configuredfunctionally identical to the brake system, for example identical inconfiguration. The data bus can comprise at least one data line. Themonitoring device can be configured to perform at least one watchdogfunction. The functionality of a “watchdog” can be described in such away that a counter is provided which increments at each step. When itreaches or overruns a limit, the microcontroller reset function isactivated. At runtime, commands are then integrated which reset thewatchdog counter. If the program hangs, the watchdog counter is nolonger reset and a reset is performed. In the present case, the firsttest signal can be a signal provided by the central control unit and,additionally or alternatively, the second test signal can be a signalprovided by the subsystem control unit or a response signal generated inresponse to a query signal previously sent by the monitoring device tothe central control unit or subsystem control unit. The first testsignal can comprise, for example, a measured value, an evaluationresult, or a protocol of the central control unit. Likewise, the secondtest signal can comprise a measured value, an evaluation result orprotocol of the subsystem control unit and, additionally oralternatively, the redundancy test signal can comprise a measured value,an evaluation result or protocol of the redundancy control unit. Themonitoring device can be configured to check or verify the measuredvalue, the evaluation result or protocol, for example by comparing itwith another measured value, evaluation result or protocol in order todetect whether the central control unit and additionally oralternatively the subsystem control unit are functioning as expected.

It is advantageous if such a switching device is configured to monitorthe functions of a plurality of control units connected to each othervia a data bus, using only one monitoring device. This enables costsavings for the brake system and additionally or alternatively for theredundant brake system.

The monitoring device can be configured to output a first control signalto a component of the brake system using the first test signal, whereinthe first control signal indicates the function of the central controlunit, and additionally or alternatively to output a second controlsignal to a component of the brake system using the second test signal,wherein the second control signal indicates the function of thesubsystem control unit, and additionally or alternatively to output aredundant control signal to a component of the brake system using theredundant test signal, wherein the redundant control signal indicatesthe function of the redundant control unit. Depending on the function ofthe central control unit, the subsystem control unit and additionally oralternatively the redundant control unit, actions can be initiated toensure or restore the function, or a replacement function can beactivated if the test signal indicates, for example, a malfunction ofthe central control unit, the subsystem control unit and additionally oralternatively the redundant control unit. For example, the respectivecontrol signal can cause a restart or power off of a defective controlunit and, additionally or alternatively, activate another control unit.

The monitoring device can be implemented in the central control unit andadditionally or alternatively in the subsystem control unit. Forexample, the monitoring device may be arranged in a common housing withthe central control unit or the subsystem control unit. The monitoringdevice can also be arranged on a common hardware component such as aprinted circuit board of the central control unit and additionally oralternatively of the subsystem control unit.

It is also advantageous if the monitoring device is arranged outside ofthe central control unit and the subsystem control unit according to oneembodiment. This means that the monitoring device can be implemented inan additional control unit of the brake system.

The monitoring device can be implemented in the redundant control unitin accordance with one embodiment. For example, the monitoring devicecan be arranged in a common housing with the redundant control unit. Themonitoring device can also be arranged on a common hardware componentsuch as a printed circuit board of the redundant control unit. Anarrangement of the monitoring device in or on the redundant control unitthus makes it possible to advantageously monitor both the brake systemand the redundant brake system.

According to one embodiment, the central control unit can be connectedor connectable for signal communication to at least one sensor andadditionally or alternatively actuator of the brake system and,additionally or alternatively, electrically connected to an operatingvoltage terminal and additionally or alternatively to a ground terminal,and additionally or alternatively the redundant control unit can beconnected or connectable for signal communication to at least the sensorand additionally or alternatively actuator and, additionally oralternatively, electrically connected to a further operating voltageterminal and additionally or alternatively to a further ground terminal.Thus, the central control unit and the redundant control unit can obtainvalues from the same sensor and additionally or alternatively the sameactuator, which values can then be checked, for example compared, by themonitoring device.

The central control unit can be connected or connectable to at least thesubsystem control unit via an electrically conductive connecting device.This allows the control units to be supplied with electrical power.

It is also advantageous if, according to one embodiment, the switchingdevice has at least one second subsystem control unit which is or can beconnected to the central control unit and additionally or alternativelyto the subsystem control unit via at least one second data bus tocontrol a second subsystem device of the brake system, wherein themonitoring device is configured to read in a third test signal from thesecond subsystem control unit in order to check a function of the secondsubsystem control unit. The second subsystem device can also be any typeof brake module of the brake system. This means that multiple subsystemcontrol units can be checked by the monitoring device, which savesadditional costs.

The subsystem control unit may be configured to control the subsystemdevice, which is formed as an electropneumatic module or a foot brakemodule of the brake system. The electropneumatic module can be asingle-channel or two-channel electropneumatic module.

Likewise, the second subsystem control unit can be configured to controlthe second subsystem device, which is formed as an electropneumaticmodule or a foot brake module of the brake system. Here, also, theelectropneumatic module can be a single-channel or two-channelelectropneumatic module.

A brake system comprises one of the switching devices described above.The brake system can be or comprise a redundant brake system, with theswitching device being implemented in the redundant brake system. Such abrake system can advantageously function with only one monitoringdevice, which can nevertheless safely monitor all control units of thebrake system and additionally or alternatively the redundant brakingsystem.

A method for operating a switching device for a brake system for avehicle comprises a reading-in step and an outputting step. In thereading-in step a first test signal is read in from a central controlunit configured to control the brake system and additionally oralternatively a second test signal is read in from a subsystem controlunit, which is connected to the central control unit via a data bus andconfigured to control a subsystem device of the brake system, andadditionally or alternatively a redundant test signal is read in from aredundant control unit, which is connected or can be connected to thecentral control unit via a further data bus and configured to control aredundant brake system for the brake system. In the outputting step, afirst control signal is output to a component of the brake system usingthe first test signal, wherein the first control signal indicates thefunction of the central control unit, and additionally or alternativelya second control signal is output to a component of the brake systemusing the second test signal, wherein the second control signalindicates the function of the subsystem control unit, and additionallyor alternatively a redundant control signal is output to a component ofthe brake system using the redundant test signal, wherein the redundantcontrol signal indicates the function of the redundant control unit.

This method can be implemented using the monitoring device presentedabove. The advantages of the monitoring device described above can alsobe realized in a technically simple and cost-effective manner by such amethod.

Exemplary embodiments of the approach presented here are explained inmore detail in the following description with reference to the figures.

In the following description of advantageous exemplary embodiments ofthe present approach, identical or similar reference signs are used forelements shown in the various figures which have similar functions,wherein no repeated description of these elements is given.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 shows a schematic illustration of a vehicle having a brake systemwith a switching device in accordance with one exemplary embodiment.

FIG. 2 shows a schematic illustration of a switching device inaccordance with one exemplary embodiment.

FIG. 3 shows a process flow diagram of a method for operating aswitching device for a brake system for a vehicle in accordance with oneexemplary embodiment.

DETAILED DESCRIPTION

FIG. 1 shows a schematic illustration of a vehicle 100 having a brakesystem 105 with a switching device 110 in accordance with one exemplaryembodiment.

According to this exemplary embodiment, the brake system 105 is formedas an electronic brake system, “EBS” for short, or according to analternative embodiment as an anti-lock braking system, “ABS” for short.According to this exemplary embodiment, the brake system 105 has atleast one subsystem device 111, 112, 113 for implementing a brakingoperation. Purely as an example, the brake system 105 according to thisexemplary embodiment has three of the subsystem devices 111, 112, 113,which according to this exemplary embodiment are formed as asingle-channel electropneumatic module, a two-channel electropneumaticmodule and/or a foot brake module. According to an alternative exemplaryembodiment, the brake system 105 has an arbitrary number of othersubsystem devices of arbitrary type.

The switching device 110 has a central control unit EBS-ECU, at leastone subsystem control unit 115, 120, 125, and a monitoring device 130.The central control unit EBS-ECU and each of the subsystem control units115, 120, 125 have a microcontroller each. The central control unitEBS-ECU is configured to control the brake system 105. The subsystemcontrol unit 115, 120, 125 is connected or can be connected to thecentral control unit EBS-ECU via a data bus DB and is configured tocontrol the subsystem device 111, 112, 113 of the brake system 105. Themonitoring device 130 is configured to read in a first test signal 135from the central control unit EBS-ECU in order to test a function of thecentral control unit EBS-ECU and configured to read in a second testsignal 140 from the subsystem control unit 115 in order to test afunction of the subsystem control unit 115.

The monitoring device 130 can also be called a “watchdog” and inaccordance with this exemplary embodiment is configured to perform atleast one watchdog function. According to one exemplary embodiment, thefirst test signal 135 is a signal provided by the central control unitEBS-ECU and/or the second test signal 140 is a signal provided by thesubsystem control unit 115 or, according to an alternative exemplaryembodiment, is a response signal generated in response to a query signalpreviously sent by the monitoring device 130 to the central control unitEBS-ECU or subsystem control unit 115. According to this exemplaryembodiment, the first test signal 135 comprises a measured value, anevaluation result or protocol of the central control unit EBS-ECU. Thesecond test signal 140 in accordance with this exemplary embodiment alsocomprises a measured value, an evaluation result or protocol of thesubsystem control unit 115. According to this exemplary embodiment themonitoring device 130 is configured to check or verify the measuredvalue, the evaluation result or protocol, for example by comparing itwith another measured value, evaluation result or protocol in order todetect whether the central control unit EBS-ECU and/or the subsystemcontrol unit 115 are functioning as expected.

Purely by way of example, the monitoring device 130 in accordance withthis exemplary embodiment is implemented in the central control unitEBS-ECU, and/or in accordance with an alternative embodiment in one ofthe subsystem control units 115, 120, 125. According to this exemplaryembodiment, the monitoring device 130 is arranged in a common housingwith the central control unit EBS-ECU or, in accordance with thealternative exemplary embodiment, in a common housing with the subsystemcontrol unit 115, 120, 125. In accordance with this exemplaryembodiment, the monitoring device 130 is arranged on a common hardwarecomponent, such as a printed circuit board of the central control unitEBS-ECU and/or subsystem control unit 115,120, 125.

The monitoring device 130 in accordance with this exemplary embodimentis also configured to output, using the first test signal 135, to acomponent of the brake system 105 a first control signal 145 thatindicates the function of the central control unit EBS-ECU and/or, usingthe second test signal 140, to output to a component of the brake system105 a second control signal 150 that indicates the function of thesubsystem control unit 115.

The switching device 110 in accordance with this exemplary embodimenthas at least one second subsystem control unit 120 which is or can beconnected to the central control unit EBS-ECU and/or the subsystemcontrol unit 120 via at least one second data bus DB to control thesecond subsystem device 112 of the brake system 105, wherein themonitoring device 130 is configured to read in a third test signal 160from the second subsystem control unit 120 in order to check a functionof the second subsystem control unit 120. The switching device 110 inaccordance with this exemplary embodiment has at least one thirdsubsystem control unit 125 which is or can be connected to the centralcontrol unit EBS-ECU and/or the subsystem control unit 120 via at leastone third data bus DB to control the third subsystem device 113 of thebrake system 105, wherein the monitoring device 130 is configured toread in a fourth test signal 165 from the third subsystem control unit125 in order to check a function of the third subsystem control unit125. The monitoring device 130 in accordance with this exemplaryembodiment is also configured to output, using the third test signal160, to a component of the brake system 105 a third control signal 170that indicates the function of the second subsystem control unit 120and/or, using the fourth test signal 165, to output to a component ofthe brake system 105 a fourth control signal 175 that indicates thefunction of the third subsystem control unit 125.

The central control unit EBS-ECU in accordance with this exemplaryembodiment is connected or can be connected to at least the subsystemcontrol unit 115, 120, 125 via an electrically conductive connectingdevice UB/GND.

The switching device 110 presented here implements ISO26262 conformanceby a central watchdog for a distributed electrical system. The switchingdevice 110 advantageously optimizes a separate monitoring function of acontrol unit EBS-ECU, 115, 120, 125, which can communicate with othercontrol units EBS-ECU, 115, 120, 125 in a system via data lines, herevia data buses DB. In principle, control units EBS-ECU, 115, 120, 125are currently being developed in accordance with the specifications ofthe Functional Safety Standard ISO26262-2. According to the standard,the internal microcontroller of the control unit EBS-ECU, 115, 120, 125must be monitored via a second entity. This second entity is implementedby the monitoring device 130 which, in accordance with one exemplaryembodiment, enables an operation or verifies calculations by a“handshake” signal by calculating the same task performed by theinternal microcontroller, and in accordance with one exemplaryembodiment comparing a result of the internal microcontroller with aresult of the monitoring device 130 and then enabling it accordingly.The control signals 145, 150, 170, 175 can be such “handshake” signals.

A second controller, hereinafter also referred to as “μC”, or anintegrated circuit, or “IC” for short, with an integrated watchdog percontrol unit EBS-ECU, 115, 120, 125, is advantageously not necessary toperform such a monitoring function, due to the monitoring device 130.The switching device 110 thus enables high costs to be saved for eitherat least one second controller or an IC with watchdog.

In order to optimize the monitoring function in the brake system 105, inthe switching device 110 presented here a watchdog functionality hasbeen implemented in the central control unit EBS-ECU, wherein thesubsystem control units 115, 120, 125 of the subsystem devices 111, 112,113 make use of the watchdog functionality. This is possible becausethese perform a constant exchange of data over the data bus DB, here aCAN-BUS (Controller Area Network bus). According to an alternativeexemplary embodiment, the watchdog functionality is performed by one ofthe attached subsystem devices 111, 112, 113 or a redundant system asdescribed in FIG. 2. In any case, the IC and/or controller component,which implements the watchdog functions, can be omitted from one or morecontrol units EBS-ECU, 115, 120, 125.

FIG. 2 shows a schematic illustration of a switching device 110 inaccordance with one exemplary embodiment. This can be the switchingdevice 110 described with reference to FIG. 1, except that according tothis exemplary embodiment the monitoring device 130 is arranged outsideof the central control unit EBS-ECU and the at least one subsystemcontrol unit 115, 120, 125.

In accordance with this exemplary embodiment, the switching device 110,in addition to or as an alternative to the at least one or the subsystemcontrol units 115, 120, 125, has a redundant control unit R-ECU in whichthe monitoring device 130 is implemented, purely as an example inaccordance with this exemplary embodiment. According to an alternativeexemplary embodiment, the monitoring device 130 is implemented in thecentral control unit EBS-ECU as described in FIG. 1. The redundantcontrol unit R-ECU is connected or can be connected to the centralcontrol unit EBS-ECU via an additional data bus DB and is configured tocontrol a redundant brake system of the same or similar configurationfor the brake system or an electronic parking brake. According to oneexemplary embodiment, the redundant control unit R-ECU is configured tobe functionally identical to the central control unit EBS-ECU.

According to this exemplary embodiment, the monitoring device 130 isconfigured to read a redundant test signal 200 from the redundantcontrol unit R-ECU in order to check a function of the redundant controlunit R-ECU. The monitoring device 130 according to this exemplaryembodiment is configured, using the redundant test signal 200, to outputto a component of the brake system a redundant control signal indicatingthe function of the redundant control unit R-ECU. The monitoring device130 according to this exemplary embodiment is also configured to read inthe first, second, third and/or fourth test signal via the additionaldata bus DB.

The central control unit EBS-ECU according to this exemplary embodimentis connected or can be connected for signal communication to at leastone sensor 205 and/or actuator 210 of the brake system and/or is or canbe electrically connected to an operating voltage terminal UB1 and/or aground terminal GND. According to this exemplary embodiment, theredundant control unit R-ECU is or can also be connected for signalcommunication to at least the sensor 205 and/or actuator 210 and/or isor can be electrically connected to an additional operating voltageterminal UB2 and/or an additional ground terminal GND.

To implement redundancy for systems such as the electrical brake systemEBS or ABS, multiple instances of these systems can be placed in thevehicle. Another possibility is to supplement the system with similarsubsystems that can provide the functionality. An example of this is tocouple an EBS with an electronic parking brake, or “EPB” for short. Inthe event of a fault, the faulty system is switched off and the secondfault-free system then takes over the task and thus establishes theredundancy. These two systems are independent of each other. They areeach developed according to the principle of functional safety and thuspossess extensive self-monitoring. Both systems are connected to eachother by a bus system and shared actuators and are used to exchangestates and data.

Multiple placement of control units or systems in vehicles involves highcosts. This approach describes a way to reduce the cost of an existingsystem using redundant systems. According to this exemplary embodiment,the principle of the “shared” watchdog is transferred to a system thatis redundantly configured.

In this exemplary embodiment, the monitoring function is performed bythe redundant control unit R-ECU. According to this exemplaryembodiment, this is connected to the central control unit EBS-ECU bydata buses DB as well as shared actuators 205 and sensors 210, whichaccording to one exemplary embodiment are used for synchronization. Forexample, a protocol can be transmitted from the central control unitEBS-ECU via the shared PCV valve using test pulses to the redundantcontrol unit R-ECU, which is controlled via the data bus DB. This canalso be used as a “shared” watchdog.

FIG. 3 shows a process flow diagram of a method 300 for operating aswitching device for a brake system for a vehicle in accordance with oneexemplary embodiment. This method 300 can be controlled or executed bythe switching devices described in one of FIG. 1 or 2. In particular, inthis context the facility for resetting at least one of the switchingdevices may also be provided.

The method 300 has a reading-in step 305 and an outputting step 310. Inthe reading-in step 305 a first test signal is read in from a centralcontrol unit configured to control the brake system and/or a second testsignal is read in from a subsystem control unit, which is connected tothe central control unit via a data bus and configured to control asubsystem device of the brake system, and/or a redundant test signal isread in from a redundant control unit, which is connected to the centralcontrol unit via a further data bus and configured to control aredundant brake system for the brake system. In the outputting step 310,a first control signal is output to a component of the brake systemusing the first test signal, wherein the first control signal indicatesthe function of the central control unit, and/or a second control signalis output to a component of the brake system using the second testsignal, wherein the second control signal indicates the function of thesubsystem control unit, and/or a redundant control signal is output to acomponent of the brake system using the redundant test signal, whereinthe redundant control signal indicates the function of the redundantcontrol unit.

The method steps presented here can be repeated and performed in adifferent order than the one described.

If an exemplary embodiment comprises an “and/or” association between afirst and a second feature, this should be read as meaning that theexemplary embodiment according to one embodiment has both the firstfeature and the second feature and in accordance with another exemplaryembodiment, it has either only the first or only the second feature.

THE LIST OF REFERENCE SIGNS IS AS FOLLOWS

DB data bus

EBS-ECU central control unit

GND ground terminal

R-ECU redundant control unit

UB/GND electrically conductive connection device

UB1 operating voltage terminal

UB2 additional operating voltage terminal

100 vehicle

105 brake system

110 switching device

111 subsystem device

112 second subsystem device

113 third subsystem device

115 subsystem control unit

120 second subsystem control unit

125 third subsystem control unit

130 monitoring device

135 first test signal

140 second test signal

145 first control signal

150 second control signal

160 third test signal

165 fourth test signal

170 third control signal

175 fourth control signal

200 redundant test signal

205 sensor

210 actuator

300 method for operating a switching device for a brake system for avehicle

305 reading-in step

310 outputting step

1-13. (canceled)
 14. A switching device for a brake system for avehicle, comprising: a central control unit for controlling the brakesystem, at least one subsystem control unit which is connected or isconnectable to the central control unit via a data bus to control asubsystem device of the brake system and/or a redundant control unitwhich is connected or is connectable to the central control unit via afurther data bus to control a redundant brake system for the brakesystem; and a monitoring device to read in a first test signal from thecentral control unit to test a function of the central control unit andwhich is configured to read in a second test signal from the subsystemcontrol unit to test a function of the subsystem control unit and/or toread in a redundant test signal from the redundant control unit in orderto test a function of the redundant control unit.
 15. The switchingdevice of claim 14, wherein the monitoring device is configured tooutput a first control signal to a component of the brake system usingthe first test signal, wherein the first control signal indicates thefunction of the central control unit, and/or to output a second controlsignal to a component of the brake system using the second test signal,wherein the second control signal indicates the function of thesubsystem control unit, and/or to output a redundant control signal to acomponent of the brake system using the redundant test signal, whereinthe redundant control signal indicates the function of the redundantcontrol unit.
 16. The switching device of claim 14, wherein themonitoring device is implemented in the central control unit and/or thesubsystem control unit.
 17. The switching device of claim 14, whereinthe monitoring device is arranged outside of the central control unitand the subsystem control unit.
 18. The switching device of claim 14,wherein the monitoring device is implemented in the redundant controlunit.
 19. The switching device of claim 14, wherein the central controlunit is connected or is connectable for signal communication to at leastone sensor and/or actuator of the brake system and/or is connectedelectrically to an operating voltage terminal and/or a ground terminaland/or the redundant control unit is connected or is connectable forsignal communication to at least the sensor and/or actuator and/orconnected electrically to a further operating voltage terminal and/or afurther ground terminal.
 20. The switching device of claim 14, whereinthe central control unit is connected or is connectable to at least thesubsystem control unit via an electrically conductive connecting device.21. The switching device of claim 14, further comprising: at least onesecond subsystem control unit which is connected or is connectable tothe central control unit and/or the subsystem control unit via at leastone second data bus to control a second subsystem device of the brakesystem, wherein the monitoring device is configured to read in a thirdtest signal from the second subsystem control unit in order to check afunction of the second subsystem control unit.
 22. The switching deviceof claim 14, wherein the subsystem control unit is configured to controlthe subsystem device that is formed as an electropneumatic module or afoot brake module of the brake system.
 23. A brake system, comprising: aswitching device, including: a central control unit for controlling thebrake system, at least one subsystem control unit which is connected oris connectable to the central control unit via a data bus to control asubsystem device of the brake system and/or a redundant control unitwhich is connected or is connectable to the central control unit via afurther data bus to control a redundant brake system for the brakesystem; and a monitoring device to read in a first test signal from thecentral control unit to test a function of the central control unit andwhich is configured to read in a second test signal from the subsystemcontrol unit to test a function of the subsystem control unit and/or toread in a redundant test signal from the redundant control unit in orderto test a function of the redundant control unit.
 24. A method foroperating a switching device for a brake system for a vehicle, themethod comprising: reading in a first test signal from a central controlunit, configured to control the brake system, and/or reading in a secondtest signal from a subsystem control unit, which is connected to thecentral control unit via a data bus and configured to control asubsystem device of the brake system, and/or reading in a redundant testsignal from a redundant control unit, which is connected or isconnectable to the central control unit via a further data bus and isconfigured to control a redundant brake system for the brake system; andoutputting a first control signal to a component of the brake systemusing the first test signal, wherein the first control signal indicatesthe function of the central control unit, and/or a second control signalto a component of the brake system using the second test signal, whereinthe second control signal indicates the function of the subsystemcontrol unit, and/or a redundant control signal to a component of thebrake system using the redundant test signal, wherein the redundantcontrol signal indicates the function of the redundant control unit. 25.A non-transitory computer readable medium having a computer program,which is executable by a processor, comprising: a program codearrangement having program code for operating a switching device for abrake system for a vehicle, by performing the following: reading in afirst test signal from a central control unit, configured to control thebrake system, and/or reading in a second test signal from a subsystemcontrol unit, which is connected to the central control unit via a databus and configured to control a subsystem device of the brake system,and/or reading in a redundant test signal from a redundant control unit,which is connected or is connectable to the central control unit via afurther data bus and is configured to control a redundant brake systemfor the brake system; and outputting a first control signal to acomponent of the brake system using the first test signal, wherein thefirst control signal indicates the function of the central control unit,and/or a second control signal to a component of the brake system usingthe second test signal, wherein the second control signal indicates thefunction of the subsystem control unit, and/or a redundant controlsignal to a component of the brake system using the redundant testsignal, wherein the redundant control signal indicates the function ofthe redundant control unit.
 26. The computer readable medium of claim25, wherein the central control unit is configured to output a firstcontrol signal to a component of the brake system using the first testsignal, wherein the first control signal indicates the function of thecentral control unit, and/or to output a second control signal to acomponent of the brake system using the second test signal, wherein thesecond control signal indicates the function of the subsystem controlunit, and/or to output a redundant control signal to a component of thebrake system using the redundant test signal, wherein the redundantcontrol signal indicates the function of the redundant control unit.